In a typical cellular radio communication system (wireless communication system), an area is divided geographically into a number of cell sites, each defined by a radio-frequency (RF) radiation pattern from a respective antenna or antenna system. The antennas in the cells are in turn coupled to some form of controller, which is then coupled to a telecommunications switch or gateway, such as a mobile switching center (MSC) and/or a packet data serving node (PDSN), as examples. These (and possibly other) elements function collectively to form a radio access network (RAN) of the wireless communication system. The switch or gateway may then be coupled with one or more transport networks, such as one or more circuit-switched networks (e.g., the public switched telephone network (PSTN)) and/or one or more packet-switched networks (e.g., the Internet).
Depending on the specific underlying technologies and architecture of a given wireless communication system, the RAN elements may take different forms. As one example, in a code division multiple access (CDMA) system configured to operate according to the IS-2000 and IS-856 standards, the antenna system is typically referred to as a base transceiver system (BTS) and is usually under the control of an entity typically referred to as a base station controller (BSC). As another example, in a universal mobile telecommunications system (UMTS) configured to operate according to the Long Term Evolution (LTE) standards, the antenna system is usually referred to as an eNodeB, and the entity that typically coordinates functionality between multiple eNodeBs is usually referred to as a mobility management entity (MME). Furthermore, other architectures and operational configurations of RANs are known to those of skill in the art, and others may hereafter be developed.
In connection with a given service provider's wireless communication system, subscribers (i.e., users) typically access the system for communication services using a communication device, such as a cellular telephone, smartphone, pager, or appropriately equipped portable computer, to name just a few examples. In a CDMA system, such a communication device is often referred to as an access terminal (AT) while, in an LTE system, that communication device is often referred to as a user equipment (UE). For simplicity, the balance of this description often refers to such communication devices as “UEs,” though it should be understood that, as used herein, this term encompasses ATs, cell phones, smart phones, air cards, and/or any other client-side wireless-communication devices that may access and communicate via one or more RANs. Similarly, “base station” is often used in the balance of this description as a term that encompasses BTSs, eNodeBs, and the like, and may also encompass their respective controller (e.g., a BSC, MME, etc.).
When a UE is positioned in a cell, it communicates via an RF air interface with the base station of the cell. Consequently, a communication path or “channel” is established between the UE and the transport network, via the air interface, the base station, and the switch or gateway. Moreover, it is noted that the actual physical configuration of a base station can vary from an integrated BTS-BSC or eNodeB unit to a distributed deployment of multiple BTSs under the control of a single BSC, or multiple eNodeBs under the control of a single MME. Regardless of whether a base station is configured to support one cell, multiple cells, multiple sectors, or some other arrangement, it is typically deployed to provide coverage over a geographical area on the scale of a few square miles and for tens to hundreds to several thousands (or more) of UEs at any one time.